Spontaneous Regression of Primary Cutaneous Diffuse Large B-Cell Lymphoma on Sequential FDG PET.

ABSTRACT: Primary cutaneous diffuse large B-cell lymphoma, leg type is a rare, aggressive lymphoma characterized by skin involvement predominantly in the lower extremities. We present a case of an elderly woman with pathology diagnosis of primary cutaneous diffuse large B-cell lymphoma, leg type with spontaneous regression without systematic therapy documented by sequential FDG PET scans and clinical follow-up.

Differentiating primary from secondary lung cancer with FDG PET/CT and extra-pulmonary tumor grade.

OBJECTIVE: Assess feasibility of differentiating primary from secondary lung cancer in patients with a solid solitary malignant pulmonary lesion (SMPL) and a previously resected extrapulmonary tumor. METHODS: Patients with pathology proven primary or secondary lung cancer from a solitary pulmonary lesion and known histopathology of extrapulmonary tumor were included. Patients with a small pulmonary lesion size, multiple malignant pulmonary nodules or an active infectious/inflammatory process were excluded. Extrapulmonary tumor grade was categorized as low, intermediate and high and was matched to FDG uptake intensity of SMPL, with FDG uptake range (SMPL/Liver SUVmax) of <0.9 for low, 0.91-1.99 for intermediate and >2.0 for high extrapulmonary tumor grade. RESULTS: Of 274 patients, 62 met the study criteria. 46 are primary and 16 are secondary lung cancer. There are 19 low, 27 intermediate and 16 high grade extrapulmonary tumors. Mean SMPL SUVmax is 8.2 ± 4.5 and SMPL/liver SUVmax is 2.4 ± 1.4. There are 37 cases (60%) with mismatched results (e.g., low FDG SMPL with intermediate or high grade extrapulmonary tumor or vice versa) and 25 matched cases (40%) that are inconclusive (e.g., low FDG with low tumor grade or high FDG with high tumor grade). Of the mismatched cases, we correctly predicted 30 cases (81%) as primary lung cancers. CONCLUSION: A mismatch between the SMPL SUVmax and the extrapulmonary tumor grade could be used to differentiate a primary lung cancer from a metastasis with reasonable accuracy. Our preliminary results support the hypothesis that FDG uptake intensity of a metastatic pulmonary lesion mirrors the tumor aggressiveness of its extrapulmonary neoplasm of origin.

Anti-inflammatory effect of biologic therapy in patients with psoriatic disease: A prospective cohort FDG PET study.

AIM: The aim of the study was to evaluate the changes in central vascular inflammation measured by FDG PET and myocardial blood flow reserve (MFR) determined by 82Rb PET following therapy with biologic agents for 6 months in patients with psoriatic arthritis (PsA) and/or cutaneous psoriasis (PsO) (group 1) and compare with PsO subjects receiving non-biologic therapy (group 2) and controls (group 3). METHODS AND RESULTS: Target-to-background ratio (TBR) by FDG PET in the most diseased segment of the ascending aorta (TBRmax) was measured to assess vascular inflammation. 82Rb PET studies were used to assess changes in left ventricular MFR. A total of 34 participants were enrolled in the study (11 in group 1, 13 in group 2, and 10 controls). A significant drop in the thoracic aorta uptake was observed in the biologic-treated group (ΔTBRmax: - .46 ± .55) compared to the PsO group treated with non-biologic therapy (ΔTBRmax: .23 ± .67). Those showing response to biologic agents maintained MFR compared to who showed no response. CONCLUSION: In a cohort of psoriasis patients treated with biologics, FDG uptake in the thoracic aorta decreased over the study period. Patients who demonstrated a significant anti-inflammatory response on FDG PET imaging maintained their MFR compared to non-responders.

Foreign body-type giant cell reaction with extensive granulation tissue and intense inflammation after chemotherapy mimicking residual lymphoma on FDG PET.

Foreign body-type giant cell reaction is typically a biological and immunological reaction to the presence of foreign bodies such as catheters, parasites or biomaterials with a collection of fused macrophages (giant cell). We reported an unusual case of [18F]FDG PET findings in diffuse large B cell lymphoma in the urinary bladder following incomplete resection and chemotherapy. As the restaging [18F]FDG PET showed intense [18F]FDG uptake in the urinary bladder at the resection site concerning for recurrence, the lesion was subsequently resected and histopathology showed extensive granulation tissue with foreign body-type giant cell reaction with no suspected foreign bodies or neoplasia.

Intensity of hypermetabolic axillary lymph nodes in oncologic patients in relation to timeline following COVID-19 vaccination.

PURPOSE: First discovered in Wuhan, China in December 2019, severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) is a highly contagious and deadly novel virus that quickly wreaked havoc throughout the world. As mass vaccination are now underway worldwide, clinicians have started to encounter a new clinical entity, COVID-19 vaccine-associated axillary lymphadenopathy. This presents a unique challenge to medical imagers, particularly in oncologic patients. METHODS: In this retrospective study, we assessed metabolic activity, size, and timeline of COVID-19 vaccine-associated axillary hypermetabolic lymph nodes in 202 oncologic patients post vaccination with 18-fluorodeoxyglucose positron emission tomography (18-FDG PET). RESULTS: When present, COVID-19 vaccine-associated hypermetabolic lymph nodes demonstrate a mean maximum standard uptake value (SUVmax) of 2.5 ± 0.3, and more common in younger patients. The metabolic activity is the most intense in the first two weeks post vaccination and diminishes over time. By approximately 5-6 weeks, only about half of the patients demonstrated appreciable, low grade uptake compared to background. CONCLUSION: Based on our preliminary results, we would recommend correlation with a history and time of vaccination and routine use of a pre-study patient questionnaire to guide interpretation to prevent over-diagnosis of axillary nodal metastases and/or unnecessary work-up in oncologic patients.

Quantitative analysis of technetium-99m-sestamibi uptake and washout in parathyroid scintigraphy supports dual mechanisms of lesion conspicuity.

PURPOSE: Proposed mechanisms of parathyroid localization in 'dual-phase' technetium-99m-sestamibi imaging include increased presence of mitochondria leading to greater uptake and slower washout compared with thyroid tissues owing to reduced expression of P-glycoprotein. Using new techniques of quantitative single-photon emission computed tomography (SPECT)/computed tomography (CT), we have measured MIBI uptake and washout to better understand factors related to conspicuity. PATIENTS AND METHODS: We retrospectively reviewed 125 consecutive patients. Early and delayed SPECT/CT images were reconstructed using a previously validated technique. Maximum standardized uptake values of parathyroid adenomas and thyroid tissue were measured, and corresponding washout rates were calculated. RESULTS: Of 53 patients with localization of parathyroid adenoma (42%), median maximum standardized uptake values were higher for parathyroid adenomas than for thyroid tissue on both early (6.43±3.78 vs. 4.43±1.93, P<0.001) and delayed (3.40±3.09 vs. 1.84±1.05, P<0.001) images, being true on a per-patient basis in 41 (77%) and 48 (91%) patients, respectively. Median washout rates were slower from parathyroid adenomas than from thyroid lobes (0.26±0.16 vs. 0.42±0.18 h, P<0.001), being true on a per-patient basis in 43 (81%) patients. Similar findings were observed in a subgroup of 37 patients with surgically-confirmed adenomas. Of the patients where initial parathyroid uptake did not exceed thyroid uptake, all 12 exhibited slower MIBI washout from the parathyroid adenomas than from the thyroid gland. The characteristics of the thyroid gland did not differ in 67 patients without parathyroid localization. CONCLUSION: Quantitative analysis of 53 patients with localization of parathyroid adenoma revealed both a generally higher initial absolute uptake and slower rate of washout of MIBI in parathyroid adenomas than in thyroid tissue. The findings may support the hypothesis that both mechanisms proposed for parathyroid conspicuity in the dual-phase examination increased mitochondrial binding and slower washout owing to reduced P-glycoprotein expression. The technique of quantitative SPECT/CT represents a powerful tool for measuring tissue uptake to elucidate the contribution of these factors to lesion conspicuity.

Dual time-point quantitative SPECT-CT parathyroid imaging using a single computed tomography: feasibility and operator variability.

OBJECTIVES: Dual-phase parathyroid scan with Tc-sestamibi is a standardized imaging method for diagnosing parathyroid adenoma and hyperplasia. Conventional planar images using a gamma camera are performed routinely in early and delayed time points, followed by a single SPECT-CT. SPECT-CT on both early and delayed time points, although clinically useful, is not commonly performed to avoid extra radiation exposure from computed tomography (CT). This study explores the feasibility of co-registering early and delayed SPECT-CT from a single CT and evaluates the most effective combination of images for co-registration. PATIENTS AND METHODS: Fourteen retrospective patients with early and delayed planar and SPECT-CT images were recruited for this validation study. Results from contemporaneous early and delayed SPECT-CT, with hardware matched registration, are considered the gold standard. Noncontemporaneous early SPECT with delayed CT and vice versa were also processed with manual alignment by an experienced and a novice operator three times each to evaluate interoperator and intraoperator variability. Maximum standardized uptake values (SUVmax) of the thyroid lobes and parathyroid adenomas were measured, and the results in terms of accuracy and precision from noncontemporaneous SPECT-CT acquisitions were evaluated. RESULTS: Good image quality from co-registered SPECT-CT acquired at different time points with the results showed no bias (P>0.5). The co-registration of early SPECT and delayed CT showed higher precision than the alternative combination. Overall, the experienced operator achieved better precision and intraoperator variability than the novice operator (reproducibility coefficient=33% SUV vs. reproducibility coefficient=54% SUV, P<0.001). CONCLUSION: Quantitative SUV measurement from early and delayed parathyroid SPECT-CT imaging is feasible, with the best result achieved by experienced operators using delayed CT in manual registration.

Osteoblastic Metastases Mimickers on Contrast Enhanced CT.

Secondary osseous involvement in lymphoma is more common compared to primary bone lymphoma. The finding of osseous lesion can be incidentally discovered during the course of the disease. However, osseous metastases are infrequently silent. Detection of osseous metastases is crucial for accurate staging and optimal treatment planning of lymphoma. The aim of imaging is to identify the presence and extent of osseous disease and to assess for possible complications such as pathological fracture of the load-bearing bones and cord compression if the lesion is spinal. We are presenting two patients with treated lymphoma who were in complete remission. On routine follow-up contrast enhanced CT, there were new osteoblastic lesions in the spine worrisome for metastases. Additional studies were performed for further evaluation of both of them which did not demonstrate any corresponding suspicious osseous lesion. The patients have a prior history of chronic venous occlusive thrombosis that resulted in collaterals formation. Contrast enhancement of the vertebral body marrow secondary to collaterals formation and venous flow through the vertebral venous plexus can mimic the appearance of spinal osteoblastic metastases.

The Imaging Findings of Erdheim-Chester Disease: A Multimodality Approach to Diagnosis and Staging.

Erdheim-Chester disease (ECD) is a rare, non-Langerhans histiocytic disorder. The most common manifestations consist of polyostotic sclerotic lesions with the majority of cases also demonstrating soft tissue involvement of the sinuses, retroperitoneum, large vessels, heart, lungs, and central nervous system. Nuclear medicine can play an important role in assessing the extent of the disease with bone scintigraphy and fluorodeoxyglucose (FDG)-positron emission tomography (PET). We present the case of a middle-aged female who initially presented with tooth pain. She subsequently underwent imaging including plain film, bone scan, computed tomography (CT), magnetic resonance imaging (MRI), and FDG-PET/CT, which showed characteristic bony involvement. Biopsy results confirmed the diagnosis of ECD.

Spectrum of FDG PET/CT findings in Burkitt lymphoma.

PURPOSE: F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) is known to be a useful diagnostic tool for staging, restaging, and monitoring therapy for lymphoma. The purpose of this retrospective study is to present a spectrum of FDG PET findings at initial presentation of Burkitt lymphoma and subsequent findings after therapy. METHOD AND MATERIALS: We retrospectively reviewed 48 patients with Burkitt lymphoma referred for a total of 160 FDG PET/computed tomography (CT) scans at our institution. We characterized the disease distribution of Burkitt lymphoma in all patients and measured representative FDG activity from initial staging scans. Therapeutic response and disease remission were assessed in patients with PET/CT and clinical follow-up studies. RESULTS: Of the 48 patients diagnosed with Burkitt lymphoma, 25 patients had FDG PET/CT scans for initial staging. All untreated lesions of Burkitt lymphoma were highly FDG avid. The mean maximum standardized uptake value of 54 representative lesions is 16.5 (range: 6-54). Twelve patients were immune compromised. The majority of patients had disease localized to the abdomen and the pelvis. Extranodal involvement was identified in more than half of the patients studied. CONCLUSION: The American (or sporadic) form of Burkitt lymphoma presented with intense hypermetabolic lesions when untreated. The information is useful in evaluating post-treatment studies in the absence of a pretreatment scan.

Initial experience with the radiotracer anti-1-amino-3-[18F]Fluorocyclobutane-1-carboxylic acid (anti-[ 18F]FACBC) with PET in renal carcinoma.

PURPOSE: Assessment of renal masses with conventional imaging may be challenging. Anti-1-amino-3-[(18)F]fluorocyclobutane-1-carboxylic acid (anti-[18F]FACBC) is a synthetic L: -leucine analog with relatively little renal excretion. The present study examines anti-[(18)F]FACBC positron emission tomography uptake in patients with renal masses. PROCEDURES: Six patients with seven renal lesions were imaged dynamically for 2 h after injection of 10-10.9 mCi (370-403 MBq) anti-[(18)F]FACBC. Lesions were evaluated qualitatively and quantitatively and correlated with histology. RESULTS: Four clear cell and one Rosai-Dorfman lesion were hypo/isointense to normal cortex; two papillary lesions in the same patient were hyperintense. Mean SUV(max) +/- SD at 30 min was 2.8 +/- 0.24 for clear cell carcinomas and 4.5 +/- 1.7 for papillary cell lesions. Mean SUV(max)/SUV(mean) ratios +/- SD of lesion to normal cortex at 30 min was 1.15 +/- 0.19 for the clear cell carcinomas and 2.3 +/- 0.84 for papillary cell. CONCLUSIONS: In this small patient sample, relative amino acid transport compared with renal cortex is elevated in renal papillary cell carcinoma but not in clear cell carcinoma.

Collimator selection, acquisition speed, and visual assessment of 131I-tositumomab biodistribution in a phantom model.

UNLABELLED: (131)I-Tositumomab has been used in treating patients with non-Hodgkin's lymphoma. It is generally recommended that high-energy collimators be used to image patients before they receive (131)I-tositumomab therapy, to determine the effective half-life for therapeutic dose and gross biodistribution. Because many nuclear medicine departments do not possess high-energy collimators, this study was designed to assess the suitability of using medium-energy collimators. The effect of scanning speed was also investigated, in an attempt to optimize the acquisition time. METHODS: Measurements were taken using an elliptic anthropomorphic torso phantom and an organ-scanning phantom fitted with fillable spheres (1-5 cm in diameter) and organ inserts. Three phantom studies were performed with differing initial (131)I concentrations in the organs, the spheres, and the thoracic and abdominal chambers. Images were acquired with both high-energy and medium-energy collimators and at acquisition speeds of 20 and 100 cm/min. The half-life for each combination (study/collimator/speed) was calculated from a linear fit of the data. The contrast of the tumor sphere was assessed using 2 identical regions, placed on and beside the sphere, and averaged over several time points. Biodistribution and image quality were visually assessed by 2 independent observers. RESULTS: Measured half-life values and visual assessment of biodistribution showed no significant difference between the 2 collimators (P = 0.32) or acquisition speeds (P = 0.85). A significant difference in the contrast of the tumor spheres was observed between the 2 collimators (P < 0.01) but not between acquisition speeds. Visual assessment of the images showed increased noise on the image acquired at 100 cm/min, although this noise did not affect lesion detectability. CONCLUSION: Measured half-life is not significantly different between the 2 collimators; hence, calculation of the residence time would be nearly the same. Medium-energy collimators can be used to accurately calculate the (131)I-tositumomab therapeutic dose and detect alterations in biodistribution.

Skeletonized internal thoracic artery harvest reduces pain and dysesthesia and improves sternal perfusion after coronary artery bypass surgery: a randomized, double-blind, within-patient comparison.

BACKGROUND: Observational studies suggest that skeletonization of the internal thoracic artery (ITA) can improve conduit flow and length and reduce deep sternal infections and postoperative pain. We performed a randomized, double-blind, within-patient comparison of skeletonized and nonskeletonized ITAs in patients undergoing coronary surgery. METHODS AND RESULTS: Patients (n = 48) undergoing bilateral ITA harvest were randomized to receive 1 skeletonized and 1 nonskeletonized ITA. Intraoperatively, ITA flow was assessed directly and with a Doppler flow probe before and after topical application of papaverine. ITA harvest time and conduit length were recorded. A blinded assessment of pain (visual analog scale) and dysesthesia (physical examination) was performed at discharge, at 2 weeks, and at a 3-month follow-up. Sternal perfusion was assessed with nuclear imaging (n = 7). Skeletonization required longer ITA harvest times (27 +/- 1 versus 24 +/- 1 minutes; P = 0.04). There was a trend toward increased ITA length in the skeletonized group (18.2 +/- 0.3 versus 17.7 +/- 0.3 cm; P = 0.09). In situ ITA flow was lower in skeletonized arteries (7.4 +/- 0.9 versus 10.1 +/- 1.0 mL/min; P = 0.01) and increased significantly after ITA division and papaverine application. Postanastomotic flows were similar between groups. Skeletonization was associated with decreased pain at the 3-month follow-up and a reduction in major sensory deficits at the 4-week and 3-month (17% versus 50%; P = 0.002) follow-ups. Baseline adjusted sternal perfusion was significantly greater by 17 +/- 6% (P = 0.03) on the skeletonized side. CONCLUSIONS: Skeletonization results in reduced postoperative pain and dysesthesia and increased sternal perfusion at follow-up but does not produce increased conduit flow. ITA skeletonization may be a strategy for reducing morbidity after CABG.